class_docstr: Simple TicTacToe Env, starts the game randomly half of the time.
code: def render(self, mode="human"):
      # Unused.
      del mode
      board_str = ""
      for i in range(3):
          for j in range(3):
              pos = self.board_state[i, j]
              if pos == -1:
                  board_str += "x"
              elif pos == 0:
                  board_str += "-"
              else:
                  board_str += "o"
          board_str += "\n"
      return board_str
  
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import gym
  from gym import spaces
  from gym.utils import seeding
  import numpy
  from tensor2tensor.data_generators import problem
  from tensor2tensor.layers import modalities
  from tensor2tensor.rl import gym_utils
label_desc: Use image node_id 5 for calling the TicTacToeEnv obj's underlying member method code with example usage: obj.render(mode) and returns: board_str